LTE Transmitter Using Analog Devices AD9361/AD9364

This example shows how to use the Xilinx® Zynq-Based Radio Support Package with MATLAB® and LTE Toolbox™ to generate an LTE transmission. The transmitted signal can be received by the companion LTE Receiver Using Analog Devices AD9361/AD9364 example if you have a second SDR platform.

Refer to the Guided Host-Radio Hardware Setup documentation for details on configuring your host computer to work with the Support Package for Xilinx® Zynq-Based Radio.

Introduction

LTE Toolbox can be used to generate standard-compliant baseband IQ downlink and uplink reference measurement channel (RMC) waveforms and downlink test model (E-TM) waveforms. These baseband waveforms can be modulated for RF transmission using SDR Radio hardware such as Xilinx Zynq-Based Radio.

In this example eight frames of a baseband RMC waveform are generated using the LTE Toolbox. A continuous RF LTE waveform is created by looping transmission of these eight frames with the Zynq® radio hardware for a user-specified time period.

% Check that LTE Toolbox is installed, and that there is a valid licenseif isempty(ver('lte')) % Check for LST install
error('zynqRadioLTETransmitter:NoLST','Please install LTE Toolbox to run this example.');
elseif ~license('test', 'LTE_Toolbox') % Check that a valid license is present
error('zynqRadioLTETransmitter:NoLST','A valid license for LTE Toolbox is required to run this example.');
end

Running the Example

The example can be run by executing zynqRadioLTETransmitterAD9361AD9364ML.m. The transmitter is controlled using the values in the txsim structure. In particular, you may wish to increase the txsim.RunTime parameter to ensure the transmission is active long enough for the receive example to execute. In this example the cell identity, and initial frame number can be customized.

Transmitter Design: System Architecture

The general structure of the LTE transmitter can be described as follows:

Generate a baseband LTE signal using LTE Toolbox

Prepare the baseband signal for transmission using the SDR hardware

Send the baseband data to the SDR hardware for upsampling and transmission at the desired center frequency

Generating the Baseband LTE Signal

The default configuration parameters defined in TS36.101 Annex A.3 [ 1 ] required to generate an RMC are provided by lteRMCDLTool. The parameters within the configuration structure rmc can then be customized as required. The baseband waveform, eNodeBOutput, a fully populated resource grid, txGrid, and the full configuration of the RMC are created using lteRMCDLTool.

The populated resource grid is displayed with channels highlighted. The power spectral density of the LTE baseband signal can be viewed using the DSP System Toolbox™dsp.SpectrumAnalyzer. As expected, the 1.4 MHz signal bandwidth is clearly visible at baseband.

The transmitter plays the LTE signal in a loop. The baseband signal is split into LTE frames of data, and a full LTE frame is transmitted using the SDR Transmitter object. The baseband LTE signal is reshaped into an M-by-N array, where M is the number of samples per LTE frame and N is the number of frames generated.

This example communicates with the radio hardware using the comm.SDRRxAD936x system object.

The transfer of baseband data to the SDR hardware is enclosed in a try/catch block. This means that if an error occurs during the transmission, the hardware resources used by the SDR System object™ are released. The sdrTransmitter System object transmits a full frame of LTE data.

Starting transmission at Fs = 1.92 MHz
## Establishing connection to hardware. This process can take several seconds.
Transmission finished

Things to Try

The companion example LTE Receiver Using Analog Devices AD9361/AD9364 can be used to decode the broadcast channel of the waveform generated by this example. Try changing the cell identity and initial system frame number and observe the detected cell identity and frame number at the receiver.

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